Port getJSSyntacticDiagnosticsForFile #1386
Description
We're missing an implementation of getJSSyntacticDiagnosticsForFile and its calling code in getSyntacticDiagnosticsForFile. The existing implementation lives in _submodules/TypeScript/src/compiler/program.ts, but needs to be ported to Go, then all tests run and the baselines accepted, which should show diffs deleted for places we've forgotten these errors.